Chemicals prevalent in everyday products may be partly to blame for the deaths of more than 1,000 ducks during the winters of 2007 and 2008, according to a study released Tuesday by federal wildlife officials.

The study, led by the U.S. Geological Survey and prompted by the U.S. Fish and Wildlife Service, began in fall 2008, after abnormally high numbers of birds were dying at various wastewater-treatment plants along the Front Range.

The ducks, mostly northern shovelers, were exposed to a class of chemicals known as surfactants that break down surface tension in water, the study concluded. The compound was found on their feathers and apparently compromised their ability to shed water.

“No one expected it,” said John Wegrzyn, a Fish and Wildlife biologist who worked on the study. “When we got the results back, we were like, ‘Really?’ “

Surfactants are added to many products, including cleaners, detergents and fabric softeners, according to the U.S. Department of Health and Human Services.

The chemical also is used as a defoaming agent in food and is in soda pop as well, Wegrzyn said.

The specific type of surfactant discovered on the birds’ feathers was polyethylene glycol. PEG is considered to be a compound of “emerging concern” by some regulators, scientists and others.

“A few short years ago, they couldn’t even measure it,” said Steve Frank, a spokesman for the Metro Wastewater Reclamation District. “Now, the list of compounds is on our horizon, and we are aware of it.”

About 92 percent of PEG is removed by Metro’s sewage-treatment system, the district’s chief chemist said.

Although the study did not blame PEG alone for the bird deaths, many of the ducks died from hypothermia or drowning because of a change in the physical makeup of their feathers. The barbules on their feathers were no longer interlocking to repel water, so it soaked their skin and feathers, Wegrzyn said.

But PEG also was found on the feathers of some birds that did not lose their ability to repel water.

Northern shovelers have unique feeding patterns compared with other ducks, Wegrzyn said. They feed mostly on microorganisms, such as algae, in water, while other ducks feed on a variety of food sources such as vegetation and insects. In addition, northern shovelers stay in the water longer to feed.

During the heavy snows and extended periods of cold weather during the winters of 2007 and 2008, much of the duck habitat in the region was covered with ice. This sent birds looking for open water at wastewater-treatment plants. There, they fed on microorganisms in the secondary clarifier and the chlorine-contact chambers.

The secondary clarifier is where single-cell organisms and bacteria eat away at the waste.

The chlorine-contact chamber is the final step before the water flows out into the South Platte River. At this stage, two chemicals are added to the water. First, a bleach equivalent is added to disinfect it, then another chemical is mixed in to neutralize it.

Neither of these chemicals contains surfactants, Frank said.

Researchers still would like to do more work to determine what combination of chemicals present in wastewater-treatment systems affects the “waterproofing” of ducks.

“We spent a lot of time, money and effort getting to this point, and we still don’t have a lot of answers,” Wegrzyn said.

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